- To this end the investigators are developing a website, EBMtrialcentral, where eligible physicians can go online and join their collaborative network. Physicians can then enroll eligible patients in this study. These will include under-served urban patients. Clinical information will be entered online (using a secure database housed at Johns Hopkins), patient consent will be obtained electronically and treatment recommendations will be randomly allocated to either 25mg daily of oral HCTZ or 12.5mg daily of oral Chlorthalidone. The investigators aim to increase to 50mg HCTZ and 25mg Chlorthalidone over 8 weeks and compare their effects on BP measured with a 24 hour monitor.